Getting 417 Error for WEB API Post method.

I have developed WEB API service in .NET. In the service I have POST request which communicates Database through Entity Framework. This post method gets called from another application. A Continuous requests are sent to this request and post method gets called accordingly. I am getting below response from the service.

417 Expectation Failed The server cannot meet the requirements of the Expect request-header field

I am not getting it for each request. For some request I am getting 200 OK. 

 

 

The service is deployed on development server.